U.S. patent number 5,114,781 [Application Number 07/451,281] was granted by the patent office on 1992-05-19 for multi-direction stretch composite elastic material including a reversibly necked material.
This patent grant is currently assigned to Kimberly-Clark Corporation. Invention is credited to Michael T. Morman.
United States Patent |
5,114,781 |
Morman |
* May 19, 1992 |
**Please see images for:
( Certificate of Correction ) ** |
Multi-direction stretch composite elastic material including a
reversibly necked material
Abstract
The present invention provides a composite elastic material
adapted to stretch in at least two directions and which includes at
least one reversibly necked material. The composite elastic
material is disclosed as having at least one elastic sheet and at
least one reversibly necked material joined to the elastic sheet at
least at three locations arranged in a nonlinear configuration, so
that the reversibly necked material is gathered between those
locations. Also disclosed is a method of producing such a composite
elastic material.
Inventors: |
Morman; Michael T. (Alpharetta,
GA) |
Assignee: |
Kimberly-Clark Corporation
(Neenah, WI)
|
[*] Notice: |
The portion of the term of this patent
subsequent to January 1, 2008 has been disclaimed. |
Family
ID: |
23791577 |
Appl.
No.: |
07/451,281 |
Filed: |
December 15, 1989 |
Current U.S.
Class: |
428/198; 428/152;
428/913; 442/328; 428/903; 442/351 |
Current CPC
Class: |
D04H
3/14 (20130101); D04H 1/56 (20130101); D04H
1/559 (20130101); B32B 5/26 (20130101); Y10T
428/24826 (20150115); B32B 3/28 (20130101); B32B
2262/0292 (20130101); B32B 7/12 (20130101); B32B
2262/0261 (20130101); B32B 2262/14 (20130101); Y10T
428/24446 (20150115); Y10T 442/626 (20150401); B32B
5/024 (20130101); B32B 2555/02 (20130101); B32B
5/026 (20130101); B32B 27/40 (20130101); B32B
5/08 (20130101); B32B 2262/067 (20130101); B32B
2307/51 (20130101); B32B 27/34 (20130101); Y10S
428/903 (20130101); B32B 27/36 (20130101); B32B
2270/00 (20130101); B32B 5/022 (20130101); B32B
2274/00 (20130101); B32B 2262/062 (20130101); B32B
27/12 (20130101); B32B 2307/726 (20130101); Y10T
442/601 (20150401); B32B 7/05 (20190101); B32B
2307/718 (20130101); Y10S 428/913 (20130101); B32B
2262/0276 (20130101); B32B 2264/02 (20130101); B32B
2555/00 (20130101); B32B 2250/20 (20130101); B32B
2307/546 (20130101); B32B 2262/0253 (20130101) |
Current International
Class: |
D04H
1/56 (20060101); D04H 13/00 (20060101); B32B
027/14 () |
Field of
Search: |
;428/152,196,197,198,252,253,284,286,903,245,287,297,298,903,913 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0019295 |
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Nov 1980 |
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EP |
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0030418 |
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Jun 1981 |
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EP |
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0127483 |
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Dec 1984 |
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EP |
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0180703 |
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May 1986 |
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EP |
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184932 |
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Jun 1986 |
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EP |
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0236091 |
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Sep 1987 |
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EP |
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0237642 |
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Sep 1987 |
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EP |
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2632875 |
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Nov 1977 |
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DE |
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2757526 |
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Jun 1979 |
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DE |
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648644 |
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Jan 1951 |
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GB |
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1532467 |
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Nov 1978 |
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GB |
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1576436 |
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Oct 1980 |
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GB |
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Primary Examiner: Bell; James J.
Attorney, Agent or Firm: Sidor; Karl V.
Claims
What is claimed is:
1. A composite elastic material capable of stretching in at least
two directions comprising:
at least one elastic sheet; and
at least one reversibly necked material joined to the elastic sheet
at least at least at three locations arranged in a nonlinear
configuration, the reversibly necked material being gathered
between at least two of the locations.
2. The material of claim 1 wherein the reversibly necked material
is a material selected from the group consisting of knitted
fabrics, loosely woven fabrics, and nonwoven materials.
3. The material of claim 1 wherein the nonwoven material is a web
selected from the group consisting of a bonded carded web of
fibers, a web of spunbonded fibers, a web of meltblown fibers, and
a multilayer material including at least one of the webs.
4. The material of claim 3 wherein the web of meltblown fibers
includes microfibers.
5. The material of claim 3 wherein the fibers comprise a polymer
selected from the group consisting of polyolefins, polyesters, and
polyamides.
6. The material of claim 5 wherein the polyolefin is selected from
the group consisting of one or more of polyethylene, polypropylene,
polybutylene, polyethylene copolymers, polypropylene copolymers,
and polybutylene copolymers.
7. The material of claim 1 wherein the necked material is a
composite material comprising a mixture of fibers and one or more
other materials selected from the group consisting of wood pulp,
staple fibers, particulates and superabsorbent materials.
8. The material of claim 1 wherein the elastic sheet comprises an
elastomeric polymer selected from the group consisting of elastic
polyesters, elastic polyurethanes, elastic polyamides, copolymers
of ethylene and at least one vinyl monomer, and elastic A-B-A'
block copolymers wherein A and A' are the same or different
thermoplastic polymer, and wherein B is an elastomeric polymer
block.
9. The material of claim 8 wherein the elastomeric polymer is
blended with a processing aid.
10. The material of claim 1 wherein the elastic sheet is an elastic
web of meltblown fibers.
11. The material of claim 10 wherein the web of meltblown fibers
includes microfibers.
12. The material of claim 1 wherein the elastic sheet is a pressure
sensitive elastomeric adhesive sheet.
13. The material of claim 12 wherein the pressure sensitive
elastomeric adhesive sheet is formed from a blend of an elastomeric
polymer and a tackifying resin.
14. The material of claim 13 wherein the blend further includes a
processing aid.
15. The material of claim 12 wherein the pressure sensitive
elastomer adhesive sheet is a pressure sensitive elastomer adhesive
web of meltblown fibers.
16. The material of claim 15 wherein the web of meltblown fibers
include microfibers.
17. A composite elastic material capable of stretching in at least
two directions comprising:
at least one elastic web of meltblown fibers; and
at least one reversibly necked nonwoven web of polypropylene fibers
joined to the elastic web at least at three locations arranged in a
nonlinear configuration, the reversibly necked nonwoven web being
gathered between at least two of the locations.
18. The material of claim 17 wherein the necked nonwoven web of
polypropylene fibers is selected from the group consisting of a
bonded carded web of polypropylene fibers, a web of spunbond
polypropylene fibers, a web of meltblown polypropylene fibers, a
hydraulically entangled web of polypropylene fibers, and a
multilayer material including at least one of the webs.
19. The material of claim 18 wherein the web of meltblown fibers
includes microfibers.
20. The material of claim 17 wherein the necked nonwoven web of
polypropylene fibers is a composite web comprising a mixture of
polypropylene fibers and one or more other materials selected from
the group consisting of wood pulp, staple fibers, particulates and
superabsorbent materials.
21. The material of claim 17 wherein the elastic sheet comprises an
elastomeric polymer selected from the group consisting of elastic
polyesters, elastic polyurethanes, elastic polyamides, copolymers
of ethylene and at least one vinyl monomer, and elastic A-B-A'
block copolymers wherein A and A' are the same or different
thermoplastic polymer, and wherein B is an elastomeric polymer
block.
22. The material of claim 21 wherein the elastomeric polymer is
blended with a processing aid.
23. The material of claim 17 wherein the elastic web of meltblown
fibers is a pressure sensitive elastomeric adhesive web of
meltblown fibers.
24. The material of claim 23 wherein the pressure sensitive
elastomer adhesive web of meltblown fibers is formed from a blend
of an elastomeric polymer and a tackifying resin.
25. The material of claim 24 wherein the blend further includes a
processing aid.
26. The material of claim 25 wherein the web of meltblown fibers
includes microfibers.
Description
FIELD OF THE INVENTION
The present invention relates to elasticized materials and a method
of making the same. Generally speaking, the present invention
relates to a composite elastic material including at least one
elastic sheet.
BACKGROUND OF THE INVENTION
Plastic nonwoven webs formed by nonwoven extrusion processes such
as, for example, meltblowing processes and spunbonding processes
may be manufactured into products and components of products so
inexpensively that the products could be viewed as disposable after
only one or a few uses. Representatives of such products include
diapers, tissues, wipes, garments, mattress pads and feminine care
products.
Some of the problems in this area are the provision of an elastic
material which is resilient and flexible while still having a
pleasing feel. One problem is the provision of an elastic material
which does not feel plastic or rubbery. The properties of the
elastic materials can be improved by forming a laminate of an
elastic material with one or more nonelastic material on the outer
surface which provide better tactile properties.
Nonwoven webs formed from nonelastic polymers such as, for example,
polypropylene are generally considered nonelastic. The lack of
elasticity usually restricts these nonwoven web materials to
applications where elasticity is not required or desirable.
Composites of elastic and nonelastic materials have been made by
bonding nonelastic materials to elastic materials in a manner that
allows the entire composite material to stretch or elongate,
typically in one direction, so they can be used in garment
materials, pads, diapers and personal care products.
In one such composite material, a nonelastic material is joined to
an elastic sheet while the elastic sheet is in a stretched
condition so that when the elastic sheet is relaxed, the nonelastic
material gathers between the locations where it is bonded to the
elastic sheet. The resulting composite elastic material is
stretchable to the extent that the nonelastic material gathered
between the bond locations allows the elastic sheet to elongate. An
example of this type of composite material is disclosed, for
example, by U.S. Pat. No. 4,720,415 to Vander Wielen et al., issued
Jan. 19, 1988.
Another elastic sheet could be used in place of the nonelastic
gatherable material in the composite of Vander Wielen et al. so
that the resulting composite material may be capable of stretching
in more than one direction. However, a composite formed solely from
elastic sheets would have the undesirable plastic or rubbery feel
which was intended to be eliminated by producing composite
materials.
DEFINITIONS
The term "elastic" is used herein to mean any material which, upon
application of a biasing force, is stretchable, that is,
elongatable, at least about 60 percent (i.e., to a stretched,
biased length which is at least about 160 percent of its relaxed
unbiased length), and which, will recover at least 55 percent of
its elongation upon release of the stretching, elongating force. A
hypothetical example would be a one (1) inch sample of a material
which is elongatable to at least 1.60 inches and which, upon being
elongated to 1.60 inches and released, will recover to a length of
not more than 1.27 inches. Many elastic materials may be elongated
by much more than 60 percent (i.e., much more than 160 percent of
their relaxed length), for example, elongated 100 percent or more,
and many of these will recover to substantially their initial
relaxed length, for example, to within 105 percent of their initial
relaxed length, upon release of the stretching force.
As used herein, the term "nonelastic" refers to any material which
does not fall within the definition of "elastic," above.
As used herein, the terms "recover" and "recovery" refer to a
contraction of a stretched material upon termination of a biasing
force following stretching of the material by application of the
biasing force. For example, if a material having a relaxed,
unbiased length of one (1) inch is elongated 50 percent by
stretching to a length of one and one half (1.5) inches the
material would be elongated 50 percent (0.5 inch) and would have a
stretched length that is 150 percent of its relaxed length. If this
exemplary stretched material contracted, that is recovered to a
length of one and one tenth (1.1) inches after release of the
biasing and stretching force, the material would have recovered 80
percent (0.4 inch) of its one-half (0.5) inch elongation. Recovery
may be expressed as [(maximum stretch length -- final sample
length)/(maximum stretch length -- initial sample length)] .times.
100.
As used herein, the term "nonwoven web" means a web that has a
structure of individual fibers or threads which are interlaid, but
not in an identifiable, repeating manner. Nonwoven webs have been,
in the past, formed by a variety of processes such as, for example,
meltblowing processes, spunbonding processes and bonded carded web
processes.
As used herein, the term "microfibers" means small diameter fibers
having an average diameter not greater than about 100 microns, for
example, having an average diameter of from about 0.5 microns to
about 50 microns, more particularly, microfibers may have an
average diameter of from about 4 microns to about 40 microns.
As used herein, the term "meltblown fibers" means fibers formed by
extruding a molten thermoplastic material through a plurality of
fine, usually circular, die capillaries as molten threads or
filaments into a high velocity gas (e.g. air) stream which
attenuates the filaments of molten thermoplastic material to reduce
their diameter, which may be to microfiber diameter. Thereafter,
the meltblown fibers are carried by the high velocity gas stream
and are deposited on a collecting surface to form a web of randomly
disbursed meltblown fibers. Such a process is disclosed, for
example, in U.S. Pat. No. 3,849,241 to Butin, the disclosure of
which is hereby incorporated by reference.
As used herein, the term "spunbonded fibers" refers to small
diameter fibers which are formed by extruding a molten
thermoplastic material as filaments from a plurality of fine,
usually circular, capillaries of a spinnerette with the diameter of
the extruded filaments then being rapidly reduced as by, for
example, eductive drawing or other well-known spunbonding
mechanisms. The production of spunbonded nonwoven webs is
illustrated in patents such as, for example, in U.S. Pat. No.
4,340,563 to Appel et al., and U.S. Pat. No. 3,692,618 to Dorschner
et al. The disclosures of both these patents are hereby
incorporated by reference.
As used herein, the term "interfiber bonding" means bonding
produced by entanglement between individual fibers to form a
coherent web structure without the use of thermal bonding. This
fiber entangling is inherent in the meltblown processes but may be
generated or increased by processes such as, for example, hydraulic
entangling or needlepunching. Alternatively and/or additionally, a
bonding agent can be utilized to increase the desired bonding and
to maintain structural coherency of a fibrous web. For example,
powdered bonding agents and chemical solvent bonding may be
used.
As used herein, the term "sheet" means a layer which may either be
a film or a nonwoven web.
As used herein, the term "necked material" refers to any material
which has been constricted in at least one dimension by applying a
tensioning force in a direction that is perpendicular to the
desired direction of neckdown. Processes that may be used to
constrict a material in such a manner include, for example, drawing
processes.
As used herein, the term "neckable material" means any material
which can be necked.
As used herein, the term "reversibly necked material" refers to a
material formed from a material that has been treated while necked
to impart memory to the material so that, when a force is applied
to extend the material to its pre-necked dimensions, the treated,
necked portions will generally recover to their necked dimensions
upon termination of the force. One form of treatment is the
application of heat. Generally speaking, extension of the
reversibly necked material is limited to extension to its
pre-necked dimensions. Therefore, unless the material is elastic,
extension too far beyond its pre-necked dimensions will result in
material failure. A reversibly necked material may include more
than one layer. For example, multiple layers of spunbonded web,
multiple layers of meltblown web, multiple layers of bonded carded
web or any other suitable material or mixtures thereof.
As used herein, the term "percent neckdown" refers to the ratio
determined by measuring the difference between the un-necked
dimension and the necked dimension of the neckable material and
then dividing that difference by the un-necked dimension of the
neckable material
As used herein, the term "composite elastic material" refers to a
multilayer material adapted to stretch and recover in at least two
directions and which has at least one elastic layer joined to a
reversibly necked material at least at three locations arranged in
a nonlinear configuration wherein the reversibly necked material is
gathered between at least two of those locations The composite
elastic material of the present invention has stretch and recovery
in at least one direction, for example, the machine direction, to
the extent that the gathers in the reversibly necked material allow
the elastic material to elongate. The composite elastic material
also has stretch and recovery in at least one other direction, for
example, in a direction generally parallel to the neckdown of the
reversibly necked material (e.g., typically in the cross-machine
direction). The composite elastic material may be stretched in that
direction to about the reversibly necked material's pre-necked
width. The composite elastic material is adapted to recover to
about its initial width (i.e., the reversibly necked material's
necked width).
The terms "elongation" or "percent elongation" as used herein
refers to a ratio determined by measuring the difference between an
elastic material's extended and unextended length in a particular
dimension and dividing that difference by the elastic material's
unextended length in that same dimension.
As used herein, the term "superabsorbent" refers to absorbent
materials capable of absorbing at least 5 grams of aqueous liquid
per gram of absorbent material (e.g., greater than 20 grams of
distilled water per gram of absorbent material) while immersed in
the liquid for 4 hours and holding substantially all of the
absorbed liquid while under a compression force of up to about 1.5
psi.
As used herein, the term "polymer" generally includes, but is not
limited to, homopolymers, copolymers, such as, for example, block,
graft, random and alternating copolymers, terpolymers, etc. and
blends and modifications thereof. Furthermore, unless otherwise
specifically limited, the term "polymer" shall include all possible
geometrical configurations of the material. These configurations
include, but are not limited to, isotactic, syndiotactic and random
symmetries.
As used herein, the term "consisting essentially of" does not
exclude the presence of additional materials which do not
significantly affect the desired characteristics of a given
composition or product. Exemplary materials of this sort would
include, without limitation, pigments, antioxidants, stabilizers,
surfactants, waxes, flow promoters, solvents, particulates and
materials added to enhance processability of the composition.
SUMMARY OF THE INVENTION
The present invention provides a method of producing a composite
elastic material adapted to stretch in at least two directions and
having one or more layers of reversibly necked material joined to
one or more layers of elastic sheet at least at two locations
wherein the reversibly necked material is gathered between the
locations.
The composite elastic material adapted to stretch in at least two
directions may be formed by elongating an elastic sheet, joining a
reversibly necked material to the elongated elastic sheet at least
at three locations arranged in a nonlinear configuration, and
relaxing the elongated elastic sheet so that the reversibly necked
material is gathered between the at least two of the locations.
The reversibly necked material may be joined to the elongated
elastic sheet by overlaying the materials and applying heat and/or
pressure to the overlaid materials. Alternatively, the layers may
by joined by using other bonding methods and materials such as, for
example, adhesives, pressure sensitive adhesives, ultrasonic
welding, hydraulic entangling high energy electron beams, and/or
lasers.
The resulting composite elastic material has stretch and recovery
in at least one direction, for example, the machine direction, to
the extent that the gathers in the reversibly necked material allow
the elastic material to elongate. The composite elastic material
also has stretch and recovery in at least one other direction, for
example, in a direction generally parallel to the neckdown of the
reversibly necked material. The neckdown of the reversibly necked
material may be in the cross-machine direction and the composite
elastic material may be stretched in that direction typically to
about the reversibly necked material's initial width. The composite
elastic material is adapted to recover to about its initial width
(i.e., the necked material's necked width).
The elastic sheet used as a component of the composite elastic
material may be a pressure sensitive elastomer adhesive sheet. If
the elastic sheet is a nonwoven web of elastic fibers or pressure
sensitive elastomer adhesive fibers, the fibers may be meltblown
fibers. The meltblown fibers may include meltblown microfibers.
The reversibly necked material used as a component of the composite
elastic material is formed from a neckable material. The neckable
material is necked by drawing in a direction generally
perpendicular to the desired direction of neck-down. Memory may be
imparted to certain necked materials so that, when a force is
applied to extend the necked materials to their pre-necked
dimensions, the materials return generally to their necked
dimensions upon termination of the force. Such memory may be
imparted to necked materials by heating the necked materials and
cooling the materials while they are still in the necked
configuration.
According to the present invention, the reversibly necked material
may be made from any neckable material that can be treated to
acquire such memory characteristics. Such neckable materials may be
in the form of, for example, bonded carded webs, spunbonded webs or
meltblown webs. The meltblown web may include meltblown
microfibers. The reversibly necked material may also include
multiple layers such as, for example, multiple spunbond layers
and/or multiple meltblown layers. The reversibly necked material
may be made of polymers such as, for example, polyolefins.
Exemplary polyolefins include polyethylene, polypropylene,
polybutylene, polyethylene copolymers, polypropylene copolymers,
polybutylene copolymers and combinations of the above.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic representation of an exemplary process for
forming a composite elastic material.
FIG. 2 is a schematic representation of an exemplary process for
forming a reversibly necked material component of a composite
elastic material.
FIG. 3A is an exemplary Differential Scanning Calorimetry scan of a
neckable material before heat treatment.
FIG. 3B is an exemplary Differential Scanning Calorimetry scan of a
reversibly necked material, i.e., after treatment while necked.
FIG. 4 is an enlarged photomicrograph of an exemplary reversibly
necked material used as a component of a composite elastic
material.
FIG. 5 is an enlarged photomicrograph of an exemplary neckable
material.
FIG. 6 is a plan view of an exemplary neckable material before
tensioning and necking.
FIG. 6A is a plan view of an exemplary reversibly necked
material.
FIG. 6B is a plan view of an exemplary composite elastic material
including a reversibly necked material while partially
stretched.
FIG. 7 is a representation of an exemplary bonding pattern used to
join components of a composite elastic material.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG. 1 of the drawings there is schematically
illustrated at 10 a process for forming a composite elastic
material capable of stretching in at least two directions.
According to the present invention, a reversibly necked material 12
is unwound from a supply roll 14 and travels in the direction
indicated by the arrow associated therewith as the supply roll 14
rotates in the direction of the arrows associated therewith. The
reversibly necked material 12 passes through a nip 16 of a first
S-roll arrangement 18 formed by the stack rollers 20 and 22.
The reversibly necked material 12 may be formed by known nonwoven
extrusion processes, such as, for example, known meltblowing
processes or known spunbonding processes, and passed directly
through the nip 16 without first being stored on a supply roll.
An elastic sheet 32 is unwound from a supply roll 34 and travels in
the direction indicated by the arrow associated therewith as the
supply roll 34 rotates in the direction of the arrows associated
therewith. The elastic sheet passes through the nip 24 of a second
S-roll arrangement 26 formed by the stack rollers 28 and 30. The
elastic sheet 32 may be formed by extrusion processes such as, for
example, meltblowing processes or film extrusion processes and
passed directly through the nip 24 without first being stored on a
supply roll.
The reversibly necked material 12 passes through the nip 16 of the
first S-roll arrangement 18 in a reverse-S path as indicated by the
rotation direction arrows associated with the stack rollers 20 and
22. From the first S-roll arrangement 18, the reversibly necked
material 12 passes through the pressure nip 40 formed by the bonder
rollers 42 and 44 of a bonder roller arrangement 46. At the same
time, the elastic sheet 32 also passes through the nip 24 of the
second S-roll arrangement 26 in a reverse-S path as indicated by
the rotation direction arrows associated with the stack rollers 28
and 30. From the second S-roll arrangement 26, the elastic sheet 32
passes through the pressure nip 40 formed by the bonder rollers 42
and 44 of a bonder roller arrangement 46.
The reversibly necked material 12 may be tensioned between the
S-roll arrangement 18 and the pressure nip of the bonder roll
arrangement 46 by controlling the peripheral linear speed of the
rollers of the first S-roll arrangement 18 to be less than the
peripheral linear speed of the bonder rollers 42 and 44 of the
bonder roller arrangement 46. Since the reversibly necked material
12 maintains its necked dimensions even without a necking force,
there is no need to maintain large amounts of tension upon the
reversibly necked material 12 in order to keep it in a necked
condition. The only tension required is tension to maintain control
of the reversibly necked material
The peripheral linear speed of the rollers of the second S-roll
arrangement 26 is controlled to be less than the peripheral linear
speed of the bonder rollers of the bonder roller arrangement 46 so
that the elastic sheet 32 is tensioned and elongated between the
second S-roll arrangement 26 and the pressure nip 40 of the bonder
roll arrangement 46.
By adjusting the difference in the speeds of the rollers, the
elastic sheet 32 is tensioned so that it maintains its elongated
condition while the reversibly necked material 12 is joined to the
elongated elastic sheet 32 during their passage through the bonder
roller arrangement 46 to form a composite elastic laminate 50 which
passes to a wind-up roll 52 which is rotating at a peripheral liner
speed that is about the same or less than the peripheral linear
speed of bonder rollers 42 and 44. Alternatively, the composite
elastic laminate 50 may pass to a holding box (not shown) to allow
the elongated elastic sheet 32 to retract and gather the necked
material 12.
Conventional drive means and other conventional devices which may
be utilized in conjunction with the apparatus of FIG. 1 are well
known and, for purposes of clarity, have not been illustrated in
the schematic view of FIG. 1.
If the bonder rollers 42 and 44 are heated bonded rollers which
thermally bond the necked material 12 and the elongated elastic
sheet 32, then upon emerging from the pressure nip 40 of the bonder
roller arrangement 46, it may be desirable for the composite
elastic material 50 to immediately pass to a holding box where the
composite elastic material 50 is maintained in a relaxed
unstretched condition for a length of time sufficient for the
elastic sheet to cool sufficiently to avoid its cooling while it is
in a stretched condition and thereby lose all or some of its
ability to contract from the stretched dimensions which it had
assumed during bonding. It has been found that elastic sheets,
particularly low basis weight elastic sheets, may loose their
ability to contract to or return to their original unstretched
dimensions if they are maintained under tension at or above their
softening temperature for any significant length of time. A brief
recovery period in a relaxed, untensioned condition immediately
after bonding has been found to be desirable to allow the low basis
weight elastic sheet to contract and gather the necked material so
the bonded web attains its elasticity in that direction to the
extent that the necked material which is gathered between the bond
locations allows the elastic sheet to elongate.
FIG. 2 illustrates an exemplary process of making the reversibly
necked material component 12 of a composite elastic material 50. A
neckable material 60 is unwound from a supply roll 62 and travels
in the direction indicated by the arrow associated therewith as the
supply roll 62 rotates in the direction of the arrows associated
therewith. The neckable material 60 passes through the nip 64 of a
drive roller arrangement 66 formed by the drive rollers 68 and 70
and then past the idler rolls 72 and 74.
The neckable material 60 may be formed by known nonwoven extrusion
processes, such as, for example, known meltblowing processes or
known spunbonding processes, and passed directly through the nip 64
without first being stored on a supply roll.
After passing through the nip 64 of the driver roller arrangement
66 and the idler rollers 72 and 74, the neckable material 60 passes
over a series of steam cans 76-86 in a series of reverse S loops as
indicated by the rotation direction arrows associated with the
steam cans. The steam cans 76-86 typically have an outside diameter
of about 24 inches although other sized cans may be used. The
contact time or residence time of the neckable material on the
steam cans to effect heat treatment will vary depending on factors
such as, for example, steam can temperature, type of material and
the basis weight of the material. For example, a necked web of
spunbond polypropylene may be passed over a series of steam cans
heated to a measured temperature from about 90.degree. to about
150.degree. C. (194.degree.-302.degree. F.) for a contact time of 5
to about 300 seconds to effect heat treatment. More particularly,
the temperature may range from about 125.degree. to about
143.degree. C. and the residence time may range from about 2 to
about 50 seconds.
Because the peripheral linear speed of the drive rollers 68 and 70
of the drive roller arrangement 66 is controlled to be lower than
the peripheral linear speed of the steam cans 76-86, the neckable
material 60 is tensioned between the steam cans 76-86 and the nip
64 of the drive roller arrangement 66. By adjusting the difference
in the speeds of the rollers, the neckable material 60 is tensioned
so that it necks a desired amount and is maintained in the necked
condition while passing over the heated steam cans 76-86. This
action imparts memory to the neckable material 60 of its necked
condition. The neckable material 60 is then cooled in the necked
condition as it passes the idler roller 88 to form the reversibly
necked material 12. That is, a material which is adapted to stretch
to at least its original, pre-necked dimensions upon application of
a stretching force in a direction generally parallel to the
direction of necking and then recover to about its reversibly
necked dimensions upon release of the stretching force.
The neckable material 60 may be a nonwoven material such as, for
example, spunbonded web, meltblown web or bonded carded web. If the
neckable material 60 is a web of meltblown fibers, it may include
meltblown microfibers. The neckable material 60 is made from any
material that can be treated while necked so that, upon application
of a force to extend the necked material to its pre-necked
dimensions, the material returns generally to its necked dimensions
upon termination of the force. Certain polymers such as, for
example, polyolefins, polyesters and polyamides may be heat treated
by, for example, heat, under suitable conditions to impart such
memory. Exemplary polyolefins include one or more of polyethylene,
polypropylene, polybutylene, poly(methyl pentene), polyethylene
copolymers, polypropylene copolymers, and polybutylene copolymers.
Polypropylenes that have been found useful include, for example,
polypropylene available from the Himont Corporation under the trade
designation PC-973, polypropylene available from the Exxon Chemical
Company under the trade designation Exxon 3445, and polypropylene
available from the Shell Chemical Company under the trade
designation DX 5A09.
In one embodiment of the present invention, the neckable material
32 is a multilayer material having, for example, at least one layer
of spunbonded web joined to at least one layer of meltblown web,
bonded carded web or other suitable material. For example, neckable
material 60 may be a multilayer material having a first layer of
spunbonded polypropylene having a basis weight from about 0.2 to
about 8 ounces per square yard (osy), a layer of meltblown
polypropylene having a basis weight from about 0.2 to about 4 osy,
and a second layer of spunbonded polypropylene having a basis
weight of about 0.2 to about 8 osy. Alternatively, the neckable
material 60 may be single layer of material such as, for example, a
spunbonded web having a basis weight of from about 0.2 to about 10
osy or a meltblown web having a basis weight of from about 0.2 to
about 8.0 osy.
The neckable material 60 may also be a composite material made of a
mixture of two or more different fibers or a mixture of fibers and
particulates. Such mixtures may be formed by adding fibers and/or
particulates to the gas stream in which meltblown fibers are
carried so that an intimate entangled commingling of meltblown
fibers and other materials, e.g., wood pulp, staple fibers and
particulates such as, for example, hydrocolloid (hydrogel)
particulates commonly referred to as superabsorbents occurs prior
to collection of the meltblown fibers upon a collecting device to
form a coherent web of randomly dispersed meltblown fibers and
other materials such as disclosed in previously referenced U.S.
Pat. No. 4,100,324.
If the neckable material 60 is a nonwoven web of fibers, the fibers
should be joined by interfiber bonding to form a coherent web
structure which is able to withstand necking. Interfiber bonding
may be produced by entanglement between individual meltblown
fibers. The fiber entangling is inherent in the meltblown process
but may be generated or increased by processes such as, for
example, hydraulic entangling or needlepunching. Alternatively
and/or additionally, thermal bonding or a bonding agent may be used
to increase the desired coherence of the web structure.
Although the present invention should not be held to a particular
theory of operation, the heat treatment should raise the neckable
material 60 to a temperature range for a specified time period
where it is believed that additional polymer crystallization occurs
while the material is in the necked condition. Because certain
types of fibers are formed by methods such as, for example,
meltblowing and spunbonding which cool the fibers very quickly, it
is believed that the polymers forming the fibers are not highly
crystallized. That is, the polymers harden before the
crystallization is complete. It is believed that additional
crystallization can be effected by increasing the temperature of
the material to a temperature below the material's melting point.
When this additional crystallization occurs while the material is
in the necked condition, it is believed that memory of the necked
condition is imparted to the material.
FIG. 3A is an exemplary Differential Scanning Calorimetry scan of a
spunbonded polypropylene material by a Model 1090 Thermal Analyzer
available from Du Pont Instruments. FIG. 3B is an exemplary
Differential Scanning Calorimetry scan of the same type of
spunbonded polypropylene material which has been necked and heat
treated. Differential Scanning Calorimetry can be used to show that
neckable materials such as, for example, spunbonded webs, which
have been necked and heat treated exhibit greater heats of fusion
than the same materials which have not been heat treated. That is,
the heat of fusion of a reversibly necked material is typically at
least about 5 percent greater than the material before being
reversibly necked. For example, from about 5 to about 15 percent
greater.
Additionally, the onset of melting occurs at lower temperatures for
necked and heat treated materials than for their non-heat treated
counterparts. That is, the onset of melting of a reversibly necked
material typically occurs at a temperature at least about 5.degree.
C. lower than for the material before being reversibly necked. For
example, at a temperature from about 5.degree. to about 15.degree.
C. lower. A greater heat of fusion is believed to result from
additional crystallization which occurs during heat treatment. A
lower temperature for onset of melting is believed to result from
imperfect or strained crystals formed during heat treatment of the
material while in the necked condition.
Tensioning and heat treatment of nonelastic, neckable material 60
also adds crimps and kinks to the material as shown in FIG. 4,
particularly when compared to the untreated material shown in FIG.
5. These crimps and kinks are believed to add to the stretch and
recovery properties of the material. Reversibly necked materials
and processes to make them are disclosed in, for example, U.S Pat.
No. 4,965,122, titled "Reversibly Necked materials" filed on Sept.
23, 1988, by M. T. Morman, incorporated herein by reference.
The elastic sheet 32 may be made from any material which may be
manufactured in sheet form. Generally, any suitable elastomeric
fiber forming resins or blends containing the same may be utilized
for the elastomeric fibers, threads, filaments and/or strands or
the nonwoven webs of elastomeric fibers, threads, filaments and/or
strands of the invention and any suitable elastomeric film forming
resins or blends containing the same may be utilized for the
elastomeric films of the invention. Useful elastic sheets may have
basis weights ranging from about 5 gsm (grams per square meter) to
about 300 gsm, for example, from about 5 gsm to about 150 gsm.
For example, the elastic sheet 32 may be made from block copolymers
having the general formula A-B-A' where A and A' are each a
thermoplastic polymer endblock which contains a styrenic moiety
such as a poly (vinyl arene) and where B is an elastomeric polymer
midblock such as a conjugated diene or a lower alkene polymer. The
elastic sheet 32 may be formed from, for example,
(polystyrene/poly(ethylene-butylene)/polystyrene) block copolymers
available from the Shell Chemical Company under the trademark
KRATON G. One such block copolymer may be, for example, KRATON
G-1657.
Other exemplary elastomeric materials which may be used to form
elastic sheet 32 include polyurethane elastomeric materials such
as, for example, those available under the trademark ESTANE from B.
F. Goodrich & Co., polyamide elastomeric materials such as, for
example, those available under the trademark PEBAX from the Rilsan
Company, and polyester elastomeric materials such as, for example,
those available under the trade designation Hytrel from E. I.
DuPont De Nemours & Company. Formation of elastic sheets from
polyester elastic materials is disclosed in, for example, U.S. Pat.
No. 4,741,949 to Morman et al., hereby incorporated by reference.
Elastic sheet 32 may also be formed from elastic copolymers of
ethylene and at least one vinyl monomer such as, for example, vinyl
acetates, unsaturated aliphatic monocarboxylic acids, and esters of
such monocarboxylic acids. The elastic copolymers and formation of
elastic sheets from those elastic copolymers are disclosed in, for
example, U.S. Pat. No. 4,803,117.
Processing aids may be added to the elastomeric polymer. For
example, a polyolefin may be blended with the elastomeric polymer
(e.g., the A-B-A elastomeric block copolymer) to improve the
processability of the composition. The polyolefin must be one
which, when so blended and subjected to an appropriate combination
of elevated pressure and elevated temperature conditions, is
extrudable, in blended form, with the elastomeric polymer. Useful
blending polyolefin materials include, for example, polyethylene,
polypropylene and polybutylene, including polyethylene copolymers,
polypropylene copolymers and polybutylene copolymers. A
particularly useful polyethylene may be obtained from the U.S.I.
Chemical Company under the trade designation Petrothaene NA 601
(also referred to herein as PE NA 601 or polyethylene NA 601). Two
or more of the polyolefins may be utilized. Extrudable blends of
elastomeric polymers and polyolefins are disclosed in, for example,
U.S. Pat. No. 4,663,220 to Wisneski et al., hereby incorporated by
reference.
The elastic sheet 32 may also be a pressure sensitive elastomer
adhesive sheet. For example, the elastic material itself may be
tacky or, alternatively, a compatible tackifying resin may be added
to the extrudable elastomeric compositions described above to
provide an elastomeric sheet that can act as a pressure sensitive
adhesive, e.g., to bond the elastomeric sheet to a tensioned,
reversibly necked nonelastic web. In regard to the tackifying
resins and tackified extrudable elastomeric compositions, note the
resins and compositions as disclosed in U.S. Pat. No. 4,787,699,
hereby incorporated by reference.
Any tackifier resin can be used which is compatible with the
elastomeric polymer and can withstand the high processing (e.g.,
extrusion) temperatures. If the elastomeric polymer (e.g., A-B-A
elastomeric block copolymer) is blended with processing aids such
as, for example, polyolefins or extending oils, the tackifier resin
should also be compatible with those blending materials. Generally,
hydrogenated hydrocarbon resins are preferred tackifying resins,
because of their better temperature stability. REGALREZ.TM. and
ARKON.TM.P series tackifiers are examples of hydrogenated
hydrocarbon resins. ZONATAK.TM.501 lite is an example of a terpene
hydrocarbon. REGALREZ.TM. hydrocarbon resins are available from
Hercules Incorporated. ARKON.TM.P series resins are available from
Arakawa Chemical (U.S.A.) Incorporated. Of course, the present
invention is not limited to use of such three tackifying resins,
and other tackifying resins which are compatible with the other
components of the composition and can withstand the high processing
temperatures, can also be used.
A pressure sensitive elastomer adhesive may include, for example,
from about 40 to about 80 percent by weight elastomeric polymer,
from about 5 to about 40 percent polyolefin and from about 5 to
about 40 percent resin tackifier. For example, a particularly
useful composition included, by weight, about 61 to about 65
percent KRATON.TM. G-1657, about 17 to about 23 percent
polyethylene NA 601, and about 15 to about 20 percent REGALREZ.TM.
1126.
The elastic sheet 32 may also be a multilayer material in that it
may include two or more individual coherent webs or films.
Additionally, the elastic sheet 32 may be a multilayer material in
which one or more of the layers contain a mixture of elastic and
nonelastic fibers or particulates. An example of the latter type of
elastic web, reference is made to U.S. Pat. No. 4,209,563,
incorporated herein by reference, in which elastomeric and
non-elastomeric fibers are commingled to form a single coherent web
of randomly dispersed fibers. Another example of such an elastic
composite web would be one made by a technique such as disclosed in
previously referenced U.S. Pat. No. 4,741,949. That patent
discloses an elastic nonwoven material which includes a mixture of
meltblown thermoplastic fibers and other materials. The fibers and
other materials are combined in the gas stream in which the
meltblown fibers are borne so that an intimate entangled
commingling of meltblown fibers and other materials, e.g., wood
pulp, staple fibers or particulates such as, for example,
hydrocolloid (hydrogel) particulates commonly referred to as
superabsorbents occurs prior to collection of the fibers upon a
collecting device to form a coherent web of randomly dispersed
fibers.
Referring again to FIG. 1, the bonder roller arrangement 46 may be
a patterned calendar roller such as, for example, a pin embossing
roller arranged with a smooth anvil roller. One or both of the
calendar roller and the smooth anvil roller may be heated and the
pressure between these two rollers may be adjusted by well-known
means to provide the desired temperature, if any, and bonding
pressure to join the reversibly necked material 12 to the elastic
sheet 32 forming a composite elastic material 50.
Reversibly necked materials may be joined to the elastic sheet 32
at least at two places by any suitable means such as, for example,
thermal bonding or ultrasonic welding. Thermal and/or ultrasonic
joining techniques are believed to soften at least portions of at
least one of the materials, usually the elastic sheet because the
elastomeric materials used for forming the elastic sheet 32 have a
lower softening point than the components of the reversibly necked
material 12. Joining may be produced by applying heat and/or
pressure to the overlaid elastic sheet 32 and the reversibly necked
material 12 by heating these portions (or the overlaid layer) to at
least the softening temperature of the material with the lowest
softening temperature to form a reasonably strong and permanent
bond between the re-solidified softened portions of the elastic
sheet 32 and the reversibly necked material 12.
The reversibly necked materials should be joined to the tensioned
elastic sheet at least at three locations which are arranged so
that upon release of the tensioning force on the elastic sheet,
puckers or gathers form in the reversibly necked material between
at least two of the locations. Additionally, the three locations
should be arranged so that when the composite elastic material is
stretched in a direction substantially parallel to the direction of
neckdown (i.e., in a direction substantially perpendicular to the
tensioning force applied to the neckable material during the
necking process), the recovery of the elastic sheet assists in the
recovery of the reversibly necked material to substantially its
necked dimensions. The three or more locations should be arranged
in a nonlinear configuration to form for example, a triangular or
polygonal pattern of locations where the reversibly necked material
is joined to the elastic sheet.
With regard to thermal bonding, one skilled in the art will
appreciate that the temperature to which the materials, or at least
the bond sites thereof, are heated for heat-bonding will depend not
only on the temperature of the heated roll(s) or other heat sources
but on the residence time of the materials on the heated surfaces,
the compositions of the materials, the basis weights of the
materials and their specific heats and thermal conductivities.
However, for a given combination of materials, and in view of the
herein contained disclosure the processing conditions necessary to
achieve satisfactory bonding can be readily determined.
Alternatively, the reversibly necked material 12 and the elastic
sheet 32 may by joined by using other bonding methods and materials
such as, for example, adhesives, pressure sensitive adhesives,
solvent welding, hydraulic entangling, high energy electron beams,
and/or lasers.
Because the tensioned elastic sheet 32 is bonded to the reversibly
necked material 12, and the reversibly necked material is
extendable in only one direction, the necked material tends to have
a limiting effect on the degree of stretch of the elastic composite
material in the direction that the reversibly necked material
cannot be extended, typically the machine direction. To the extent
that the reversibly necked material exhibits some resistance to
being gathered, the elastic sheet will be unable to fully recover
to its unstretched dimension once it is joined to the reversibly
necked material. This requires that the distance that the elastic
sheet is capable of stretching when it is joined to the reversibly
necked material be greater than the desired stretch of the elastic
composite material in the direction that the necked material cannot
be easily extended (e.g., the machine direction). For example, if
it is desired to prepare an elastic composite material that can be
elongated about 100 percent in the machine direction (i.e.,
stretched to a length that is about 200 percent of its initial
relaxed length), it may be necessary to stretch a 100 cm length of
elastic web in the machine direction to a length of, for example,
220 cm (120 percent elongation) and bond the stretched elastic web
at least at three locations (arranged in spaced-apart non-linear
configuration) to a 220 cm length of reversibly necked material.
The bonded composite elastic material is then allowed to relax and
even if the elastic sheet is capable of recovering to its original
100 cm length, the reversibly necked material bonded thereto will
inhibit full recovery and the composite may relax to a length of
say, 110 cm. Puckers or gathers will form in the reversibly necked
material between at least two of the bond points. The resulting 110
cm length of composite material is stretchable in the machine
direction to its 220 cm length to provide a composite material that
can be elongated about 100 percent in the machine direction (i.e.,
stretched to a length that is about 200 percent of its initial
relaxed length). The initial length of the reversibly necked
material limits, in this hypothetical example, the attainable
machine direction elongation of the composite material because the
reversibly necked material would act as a "stop" to prevent further
or excessive stretching of the elastic sheet in the machine
direction under the effect of stretching forces which are less than
the failure strength of the reversibly necked, gathered
material.
The relation between the original dimensions of the reversibly
necked material 12 to its dimensions after neckdown determines the
approximate limits of stretch of the composite elastic material in
the direction of neckdown, typically the cross-machine
direction.
For example, with reference to FIGS. 6, 6A, and 6B, if it is
desired to prepare a composite elastic material including a
reversibly necked material which is stretchable to a 150%
elongation (i.e., stretched to a length that is about 250 percent
of its initial relaxed length) in a direction generally parallel to
the neckdown of the neckable material (e.g. cross-machine
direction) and stretchable to a 100% elongation (i.e., stretched to
a length that is about 200 percent of its initial relaxed length)
in the perpendicular direction (e.g., machine direction), a width
of neckable material shown schematically and not necessarily to
scale in FIG. 6 having a width "A" such as, for example, 250 cm, is
tensioned so that it necks down to a narrower width "B" of about
100 cm as shown in FIG. 6A. The tensioning forces are shown as
arrows C and C' in FIG. 6A. The tensioned, necked material is heat
treated while necked to impart a memory of its necked configuration
shown in FIG. 6A. The resulting reversibly necked material is then
joined in the necked configuration to an elastic sheet which is
about the same width "B" as the tensioned, necked material and
which is stretchable in the cross-machine direction at least to
about the same width "A" as the original pre-necked dimensions of
the necked material. For example, the elastic sheet may be
approximately 100 cm and be stretchable to at least a width of 250
cm. The tensioned, necked material shown in FIG. 6A and the elastic
sheet (not shown) are overlaid and joined at least at three spaced
apart locations arranged in a nonlinear configuration while the
elastic sheet is maintained at a machine-direction elongation of
about 120 percent (i.e., stretched about 220 percent of its initial
relaxed machine-direction dimension) because, as previously noted,
the necked material tends to prevent the elastic sheet from
retracting fully to its original length in the machine
direction.
The joined layers are allowed to relax causing puckers or gathers
to form in the reversibly necked material between at least two of
the bond locations. The resulting composite elastic material shown
schematically and not necessarily to scale in FIG. 6B has a width
"B" of about 100 cm and is stretchable to at least the original 250
cm width "A" of the neckable material for an elongation of about
150 percent (i.e., stretchable to about 250 percent of its initial
necked width "B"). The composite elastic material is adapted to
recover to its initial width "B" of about 100 cm because recovery
of the elastic sheet to its initial width "B" assists the attached
reversibly necked material in recovering to its necked width "B".
Additionally, the composite elastic material is stretchable to
about 100 percent in the machine direction which is the extent that
the gathers or puckers in the reversibly necked material allow the
elastic sheet to elongate in that direction. As can be seen from
the example, the distance that the elastic sheet should be capable
of stretching in the cross-machine direction before it is joined to
the reversibly necked material needs only to be as great as the
distance that the composite elastic material is desired to stretch
in the cross-machine direction. However, as previously noted, the
distance that the elastic sheet should be capable of stretching in
the machine direction before it is joined to the reversibly necked
material should be greater than the distance that the composite
material is desired to stretch in the machine direction.
The gathers in the reversibly necked material may allow the
composite elastic material to have stretch and recovery in a range
of directions that are not substantially parallel to the machine
direction, for example, in a direction that differs from the
machine direction by about 45.degree.. Similarly, the neckdown of
the reversibly necked material may allow the composite elastic
material to have stretch and recovery in a range of directions that
are not substantially parallel to the direction of neckdown, for
example, in a direction that differs from the direction of neckdown
by about 45.degree.. Because of the gathers in the reversibly
necked material and the direction of neckdown may be aligned to
allow stretch and recovery in generally perpendicular directions,
and because the gathers and neckdown allow stretch and recovery in
a range of directions, the composite elastic material may be
adapted to have stretch and recovery in substantially all
directions along the length and width of the material.
EXAMPLES 1-5
The composite elastic materials of examples 1-5 were made by
joining an elastic sheet to at least one reversibly necked
material. Tables 1, 3, 6, 8, and 10 provide Grab Tensile Test data
for control samples and composite elastic necked-bonded material
samples. The Grab Tensile Tests were performed on a constant rate
of extension tester, Instron Model 1122 Universal Testing
Instrument, using 4 inch by 6 inch samples. The jaw faces of the
tester were 1 inch by 1 inch and the crosshead speed was set at 12
inches per minute. The following mechanical properties were
determined for each sample: Peak Load, Peak Total Energy Absorbed
and Percent Elongation.
The samples were also cycled on the Instron Model 1122 with
Microcon II - 50 kg load cell and the results reported on Tables 2,
4, 5, 7, 9, and 11. The jaw faces of the tester were 3 inches wide
by 1 inch high (i.e., in the direction to be tested) in this
cycling test so the samples were cut to 3 inches by 7 inches (i.e.,
7 inches in the direction to be tested) and weighed individually in
grams. A 4 inch gauge length was used. Chart and crosshead speeds
were set for 20 inches per minute and the unit was zeroed, balanced
and calibrated according to the standard procedure. The maximum
extension limit for the cycle length was set at a distance
determined by calculating 56 percent of the "elongation to break"
from the Grab Tensile Test. The samples were cycled to the
specified cycle length four times and then were taken to break on
the fifth cycle. The test equipment was set to measure Peak Load in
pounds force, and Peak Energy Absorbed in inch pounds force per
square inch for each cycle. On the fifth cycle (cycle to break),
the Peak Elongation, Peak Load, and Peak Total Energy Absorbed were
measured. The area used in the energy measurements (i.e., the
surface area of material tested) is the gauge length (four inches)
times the sample width (3 inches) which equals twelve square
inches. The results of the Grab Tensile tests and cycle tests have
been normalized for measured basis weight.
Peak Total Energy Absorbed (TEA) as used in the Examples and
associated Tables is defined as the total energy under a stress
versus strain (load versus elongation) curve up to the point of
"peak" or maximum load. TEA is expressed in units of
work/(length).sup.2 or (pounds force * inch)/(inches).sup.2. These
values have been normalized by dividing by the basis weight of the
sample in ounces per square yard (osy) which produces units of
[(lbs.sub.f * inch)/inch.sup.2 ]/osy.
Peak Load as used in the Examples and associated Tables is defined
as the maximum load or force encountered in elongating the sample
to a specified elongation or to break. Peak Load is expressed in
units of force (lbs.sub.f) which have been normalized for the basis
weight of the material resulting in a number expressed in units of
lbs.sub.f /(osy).
Elongation or Peak Elongation has the same general definition as
previously set forth in the "Definition" section, and may be more
specifically defined for the Examples and associated Tables as the
relative increase in length of a specimen during the tensile test
at Peak Load. Peak Elongation is expressed as a percentage, i.e.,
[(increase in length)/(original length)] .times. 100.
Permanent Set after a stretching cycle as used in the Examples and
associated Tables is defined as a ratio of the increase in length
of the sample after a cycle divided by the maximum stretch during
cycling. Permanent Set is expressed as a percentage, i.e., [(final
sample length - initial sample length)/(maximum stretch during
cycling - initial sample length)].times. 100. Permanent Set is
related to recovery by the expression [permanent set = 100 -
recovery] when recovery is expressed as a percentage.
In Tables 2, 4, 5, 7, 9, and 11, (which provide the results of the
cycle testing), the value reported for the composite material's
Permanent Set in the "Perm Set" row and in the column titled "To
Break" is the value for Peak Elongation (i.e., peak elongation to
break) measured during the fifth (final) stretch cycle. In those
same Tables, the cycle test results reported in the "To Break"
column for the elastomeric sheet are the values read from the
Instron test equipment when the elastomeric sheet was elongated to
the Peak Elongation (i.e., elongation at peak load when the sample
was tested to break) measured during the fifth (final) stretch
cycle for the composite elastic material which incorporated that
particular elastomeric sheet.
EXAMPLE 1
Reversibly Necked Spunbonded Materials
Several neckable webs of conventionally produced spunbonded
polypropylene having a basis weight of about 0.4 ounces per square
yard (osy) were tested on an Instron Model 1122 Universal Testing
Instrument. The average results for 4 samples are reported in Table
1 under the heading "Spunbond Control No. 1". The machine direction
total energy absorbed is given in the column of Table 1 entitled
"MD TEA". The machine direction peak load is given in the column
entitled "MD Peak Load". The machine direction peak elongation is
given in the column entitled "MD Peak Elong". The cross-machine
direction total energy absorbed is given in the column entitled "CD
TEA". The cross-machine direction peak load is given in the column
entitled "CD Peak Load". The cross-machine direction peak
elongation is given in the column entitled "CD Peak Elong".
One roll of above-described spunbond web having a basis weight of
about 0.4 osy and a width of about 75 inches was unwound at a speed
of about 146-147 feet/minute (fpm) and passed over a series of
three steam can arrangements each containing 12 steam cans rotating
at speeds of 161, 168 and 175 fpm respectively. The spunbond web
was wound on a take-up roll at a speed of 178 fpm. The difference
in speed between the unwind and the take-up rolls caused the
material to neck to a final width of about 29-31 inches for a
percent neckdown of about 61 to about 59 percent. The steam cans of
the first two arrangements were kept at room temperature. The steam
cans of the last arrangement were kept at a temperature of about
275.degree. F. so that the spunbond web was heated while in the
necked condition. Grab Tensile Testing was performed on the Instron
Model 1122 Universal Testing Instrument and the results are
reported in Table 1 under the heading "Reversibly Necked Spunbond
No. 1A".
A different roll of the above-described Lurgi spunbond web having a
basis weight of about 0.4 osy and a width of about 66 inches was
unwound at a speed of about 142 (fpm) and passed over the series of
three steam can arrangements each containing 12 steam cans rotating
at speeds of 159, 168 and 172 fpm respectively. The spunbond web
was wound on a take-up roll at a speed of 176 fpm. The difference
in speed between the unwind and the take-up rolls caused the
material to neck to a final width of about 26 inches for a percent
neckdown of about 60 percent. The steam cans of the first two
arrangements were kept at room temperature. The steam cans of the
last arrangement were kept at a temperature of about 284.degree. F.
so that the spunbond web was heated while maintained in the
stretched condition. Grab Tensile Testing was performed on the
Instron Model 1122 Universal Testing Instrument and the results are
reported in Table 1 under the heading "Reversibly Necked Spunbond
No. 1B".
Elastic Sheet
A blend of about 63% by weight KRATON G-1657, 20% polyethylene
NA-601 and 17% REGALREZ 1126 having a melt flow of about 15 grams
per ten minutes when measured at 190.degree. C. and under a 2160
gram load; an elongation of about 750%; a modulus of elongation at
100% of about 175 psi; and a modulus of elongation at 300% of about
225 psi was formed into an elastic sheet of meltblown fibers
utilizing conventional recessed die tip meltblowing process
equipment. A four-bank meltblowing die arrangement was operated
under the following conditions: die zone temperature from about 503
to about 548.degree. F.; die polymer melt temperature from about
491 to about 532.degree. F.; primary air temperature from about 544
to about 557 of pressure at die inlet/tip from about 85 to about
140 psig; forming vacuum about 2 inches of water; vertical forming
distance about 11 inches, forming wire speed about 61 feet per
minute and winder speed about 67 feet per minute. An elastic web of
meltblown fibers was formed having a basis weight of about 125
grams per square meter (gsm) and a width of about 52 inches. The
elastic meltblown was formed on a polypropylene film for ease of
handling. The elastic sheet (minus the polypropylene film) was
tested on the Instron Model 1122 Universal Testing Instrument and
the results are given in Tables 1 and 2 under the heading "
Elastomer Control No. 1." In Table 2, data collected in the last
cycle (i.e. "To Laminate Break") for the Elastomer Control material
was read at the cross-machine break elongation and the machine
direction break elongation of NSBL No. 1 material shown at Table 1
as 217% and 83% respectively.
The 52 inch wide elastic web of meltblown fibers was pre-stretched
utilizing a "22 inch Face Coating Line rewinder" made by the
Black-Clawson Company. The unwind speed was set at about 30 fpm and
the wind-up speed was set at about 63 fpm causing the material to
neck or constrict. As the necked elastic material approached the
wind-up roll, the material was slit to a width of about 30.5
inches. The slit pre-stretched sheet was tested on the Instron
Model 1122 Universal Testing Instrument and the results are given
in Table 1 under the heading "Prestretched Elastomer No. 1." From
Table 1 it can be seen that stretching the elastomer had little
affect on its physical properties.
Composite Elastic Material
The roll of "Reversibly Necked Spunbond No. 1A" was put on the top
position of a three position roll unwind apparatus and the top
unwind resistance brake was set at 66 pounds per square inch (psi).
The roll of "Prestretched Elastomer No. 1." was placed on the
middle position. The roll of "Reversibly Necked Spunbond No. 1B"
was put on the bottom position of the three position roll unwind
apparatus and the bottom unwind resistance brake was set at 85 psi.
The bonder rolls operated at a speed of about 30 feet/minute and
the elastic sheet unwind roll operated at an speed of about 28
feet/minute.
The necked spunbonded material and the elastic meltblown sheet were
joined utilizing a heated bonder roller arrangement. The
temperature of the calendar roller and anvil roller was set at
127.degree. F. and the nip pressure was 20 pounds per square inch
(psi) which was equivalent to about 355 pounds per linear inch
(pli). FIG. 7 shows the pattern of the engraved calendar roller
enlarged about 5 times. The bond pattern of the engraved roller had
approximately 300 pins or bond points per square inch which
produced a bond area of about 15 percent. The lines connecting the
pins or bond points are drawing lines and are not present in the
engraving pattern of the calender roller. The composite material
was allowed to relax immediately after bonding.
The multi-direction stretch composite elastic material produced in
this manner was tested on the Instron Model 1122 Universal Testing
Instrument and the results are given in Tables 1 and 2 under the
heading "NSBL No. 1". Compared to the neckable "Spunbond Control
No. 1", all Grab Tensile Test results were lower for the "NSBL No.
1" except for the machine direction elongation and the
cross-machine direction elongation which were significantly
increased. Compared to the reversibly necked spunbonded control
material (Reversibly Necked Spunbond Control Nos. 1A and 1B), all
Grab Tensile Test results were lower for the composite elastic
material except for the machine direction elongation and the
cross-machine direction elongation which were significantly
increased. Compared to the elastic meltblown sheet, the composite
elastic material has about the same values during cycling but has
higher Total Energy Absorbed and Peak Load at the breaking point of
the composite elastic material (Table 2).
COMPARATIVE EXAMPLE 1A
A composite elastic material was prepared utilizing the same
materials as Example 1 except that the elastic sheet had a basis
weight of 75 grams and was not prestretched before it was bonded to
the reversibly necked spunbonded polypropylene.
The reversibly necked spunbonded polypropylene webs and the
meltblown elastic sheet were joined utilizing a heated bonder
roller arrangement at the same temperature and pressure and using
the same bond pattern as in Example 1. No braking force was applied
to any of the unwind rolls except to provide enough tension to
maintain control of the materials. Thus, the reversibly necked
spunbond material remained at about its necked width and the
elastic sheet remained unstretched.
The resulting composite elastic material was tested on the Instron
Model 1122 Universal Testing Instrument and the results are given
in Tables 1 and 2 under the heading "Composite No. 1". When
compared to NSBL No. 1, the properties of Composite No. 1 were not
changed much except that the cross-machine direction elongation was
greater for Composite No. 1and the machine direction elongation was
greater for NSBL No. 1.
EXAMPLE 2
A roll of "Reversibly Necked Spunbond No. 1A" from Example 1 having
a basis weight of 0.4 osy was put on the top position of a three
position roll unwind apparatus. A roll of the pre-stretched elastic
meltblown sheet of Example 1 having a basis weight of 125 gsm
(Prestretched Elastomer No. 1) was placed on the middle position. A
roll of "Reversibly Necked Spunbond No. 1B", also from Example 1,
was put on the bottom position of the three position roll unwind
apparatus. The bonder rolls operated at a speed of about 31
feet/minute and the elastic sheet unwind roll operated at a speed
of about 20 feet/minute to further elongate the elastic sheet. The
reversibly necked spunbonded polypropylene webs and the meltblown
elastic sheet were joined utilizing a heated bonder roller
arrangement at the same temperature and pressure and using the same
bond pattern as in Example 1. The Grab Tensile test properties of
the material were measured utilizing an Instron Model 1122
Universal Testing Instrument and the results are reported in Tables
3, 4 and 5 under the heading "NSBL No. 2A".
COMPARATIVE EXAMPLE 2
A composite elastic material was prepared using the same material
and procedures of Example 2 except that the bonder rolls operated
at a speed of about 31 feet/minute and the elastic sheet unwind
roll operated at a speed of about 10 feet/minute to further
elongate the elastic sheet The reversibly necked spunbonded
polypropylene webs and the meltblown elastic sheet were joined
utilizing a heated bonder roller arrangement at the same
temperature and pressure and using the same bond pattern as in
Example 2. The Grab Tensile test properties of the material were
measured utilizing an Instron Model 1122 Universal Testing
Instrument and the results are reported in Tables 3, 4 and 5 under
the heading "NSBL No. 2B". Comparing NSBL No. 2A to NSBL No. 2B
shows that the peak TEA of NSBL 2A is greater because that material
is cycled to a longer length. The increase in peak TEA can also be
seen for the Elastomer Control No. 1when cycled in the machine
direction to 46%, 84% and 167%. It can be seen from Tables 4 and 5
that NSBL Nos. 2A and 2B have higher total energy and peak load
during the final cycle because of the "permanent stop" (i.e., limit
on the ability elastic sheet to stretch) caused by the spunbond
layers of the composite.
EXAMPLE 3
A composite elastic material was prepared using the same materials
and procedures of Example 1 except that the elastic meltblown sheet
was pre-stretched at an unwind speed of 30 fpm and wind-up speed of
88 fpm for a draw ratio of about 2.9. The bonder rolls operated at
a speed of about 30 feet/minute and the elastic sheet unwind roll
operated at a speed of about 20 feet/minute to further elongate the
elastic material. The reversibly necked spunbonded polypropylene
webs and the prestretched meltblown elastic sheet were joined
utilizing smooth bonding rolls to provide maximum bond surface
area. The temperature of the bonder rolls was 90.degree. F. and the
calendar pressure was 20 psi (equivalent to about 355 pli). The
Grab Tensile test properties of the material were measured
utilizing an Instron Model 1122 Universal Testing Instrument and
the results are reported in Tables 6 and 7 under the heading "NSBL
No. 3A".
COMPARATIVE EXAMPLE 3
A composite elastic material was prepared using the same materials
and procedures of Example 3 including the elastic meltblown sheet
that was pre-stretched at an unwind speed of 30 fpm and wind-up
speed of 88 fpm. The bonder rolls operated at a speed of about 30
feet/minute and the elastic sheet unwind roll also operated at a
speed of about 30 feet/minute so there was no additional stretching
of the elastic sheet. As in Example 3, the reversibly necked
spunbonded polypropylene webs and the prestretched meltblown
elastic sheet were joined utilizing smooth bonding rolls to provide
a large bond surface area. The temperature of the bonder rolls was
90.degree. F. and the calendar pressure was 20 psi (equivalent to
about 355 pli). The Grab Tensile test properties of the material
were measured utilizing an Instron Model 1122 Universal Testing
Instrument and the results are reported in Tables 6 and 7 under the
heading "NSBL No. 3B". As can be seem from Tables 6 and 7, the
cross-machine direction stretch properties are affected very little
by the amount that the elastic sheet is stretched in the machine
direction.
EXAMPLE 4
A composite elastic material was prepared using the same materials
and procedures of Example 1. The bonder rolls operated at a speed
of about 35 feet/minute and the elastic sheet unwind roll operated
at a speed of about 17 feet/minute to further elongate the elastic
material. The reversibly necked spunbonded polypropylene webs and
the prestretched meltblown elastic sheet were joined utilizing
smooth bonding rolls to provide maximum bond surface area. The
temperature of the bonder rolls was 90.degree. F. and the calendar
pressure was 60 psi. The Grab Tensile test properties of the
material were measured utilizing an Instron Model 1122 Universal
Testing Instrument and the results are reported in Tables 8 and 9
under the heading "NSBL No. 4A".
COMPARATIVE EXAMPLE 4
A composite elastic material was prepared using the same materials
and procedures of Example 1. The bonder rolls operated at a speed
of about 35 feet/minute and the elastic sheet unwind roll also
operated at a speed of about 35 feet/minute so there would be no
additional stretching of the elastic material. The reversibly
necked spunbonded polypropylene webs and the prestretched meltblown
elastic sheet were joined utilizing smooth bonding rolls to provide
the maximum bonding area. The temperature of the bonder rolls was
90.degree. F. and the calendar pressure was 60 psi. The Grab
Tensile test properties of the material were measured utilizing an
Instron Model 1122 Universal Testing Instrument and the results are
reported in Tables 8 and 9 under the heating "NSBL No. 4B". As can
be seen from Tables 8 and 9, the use of smooth bonding rolls
instead of a diamond pattern calendar had little effect on the
tensile properties of the resulting composite elastic
materials.
EXAMPLE 5
A composite elastic material was prepared using the same materials
and procedures of Example 2. The heated bonder roller temperature
was 90.degree. F. The bonder rolls operated at a speed of about 31
feet/minute and the elastic sheet unwind roll operated at a speed
of about 20 feet/minute to further elongate the elastic material
before being joined to the reversibly necked webs. The reversibly
necked spunbonded polypropylene webs and the prestretched meltblown
elastic sheet were joined utilizing the diamond pattern roller
described in Example 1. The calendar pressure was 20 psi
(equivalent to about 355 pli). The Grab Tensile test properties of
the material were measured utilizing an Instron Model 1122
Universal Testing Instrument and the results are reported in Tables
10 and 11 under the heading "NSBL No. 2A".
COMPARATIVE EXAMPLE 5
A composite elastic material was prepared using the same materials
and procedures of Example 3. Smooth bonder rollers were used to
provide maximum bond surface area. The bonder rolls operated at a
speed of about 30 feet/minute and the elastic sheet unwind roll
operated at a speed of about 20 feet/minute to further elongate the
elastic material before being joined to the reversibly necked webs.
The temperature of the smooth bonder rolls was 90.degree. F. and
the calendar pressure was 20 psi (equivalent to about 355 pli). The
Grab Tensile test properties of the material were measured
utilizing an Instron Model 1122 Universal Testing Instrument and
the results are reported in Tables 10 and 11 under the heading
"NSBL No. 3A". As can be seen from Tables 10 and 11, the use of
smooth bonder rollers instead of the diamond pattern calendar
roller had little effect on the Grab Tensile test properties.
However, the use of smooth bonder rolls resulted in lower values of
Peak TEA and Peak Load during the cross-machine direction cycle
testing. Those materials also had higher values for permanent set
during cross-machine direction cycling than for the diamond pattern
roll bonded materials.
TABLE 1
__________________________________________________________________________
Reversibly Reversibly Necked Spunbond Necked Spunbond Elastomer
Composite Prestretched Spunbond Grab Tensiles: No. 1 A No. 1 B NSBL
No. 1 Control No. 1 No. 1 Elastomer No. Control No.
__________________________________________________________________________
1 MD TEA .32 .+-. .15 .25 .+-. .07 .21 .+-. .04 1.53 .+-. .25 .14
.+-. .03 1.25 .+-. .27 .98 .+-. .2 MD Peak Load 9.8 .+-. .8 8.2
.+-. 1.2 3.4 .+-. .4 1.75 .+-. .18 5.0 .+-. .06 1.41 .+-. .16 15.1
.+-. 1 MD Peak Elong 19 .+-. 6 18 .+-. 2 83 .+-. 5 550 .+-. 50 25
.+-. 2 550 .+-. 80 40 .+-. 6 CD TEA .55 .+-. .22 .52 .+-. .10 .63
.+-. .14 1.44 .+-. .18 .52 .+-. .04 1.35 .+-. .27 .95 .+-. .2 CD
Peak Load 5.0 .+-. .6 4.2 .+-. 2.6 .+-. .14 1.58 .+-. .08 2.3 .+-.
.2 1.41 .+-. .13 14 .+-. 1 CD Peak Elong 172 .+-. 20 188 .+-. 14
217 .+-. 30 560 .+-. 60 228 .+-. 13 623 .+-. 70 50
__________________________________________________________________________
.+-. 5
TABLE 2
__________________________________________________________________________
CYCLE: 1 2 3 4 To Break
__________________________________________________________________________
Composite No. 1 Cycled in the cross-machine direction ot 128%
Elongation Peak TEA .148 .+-. .01 .077 .+-. .005 .07 .+-. .005 .07
.+-. .005 .519 .+-. .06 Peak Load .69 .+-. .06 .61 .+-. .05 .58
.+-. .05 .57 .+-. .05 2.04 .+-. .08 Perm Set 10.5 12 13 14 227 .+-.
14 NSBL No. 1 Cycled in the cross-machine direction to 121%
Elongation Peak TEA .199 .+-. .014 .096 .+-. .005 .087 .+-. .003
.082 .+-. .004 .483 .+-. .044 Peak Load 1.27 .+-. .16 1.13 .+-. .15
1.1 .+-. .13 1.04 .+-. .13 2.46 .+-. .14 Perm Set 12 .+-. 1 14 .+-.
.5 14 .+-. .5 16 .+-. 1 184 .+-. 10 Elastomer Control No. 1 Cycled
in the cross-machine direction to 121% Elongation Peak TEA .17 .+-.
.004 .115 .+-. .002 .11 .+-. .001 .104 .+-. .003 .24 .+-. .003 Peak
Load .62 .+-. .01 .58 .+-. .01 .57 .+-. .01 .56 .+-. .003 .725 .+-.
.003 Perm Set NSBL No. 1 Cycled in the cross-machine direction to
121% Elongation Peak TEA .199 .+-. .014 .096 .+-. .005 .087 .+-.
.003 .082 .+-. .004 .483 .+-. .044 Peak Load 1.27 .+-. .16 1.13
.+-. .15 1.1 .+-. .13 1.04 .+-. .13 2.46 .+-. .14 Perm Set 12 .+-.
1 14 .+-. .5 14 .+-. .5 16 .+-. 1 184 .+-. 10 Elastomer Control No.
1, Cycled in the machine direction to 46% Elongation Peak TEA 0.42
.+-. .002 .034 .+-. .002 .033 .+-. .002 .032 .002 .111 .+-. .003
Peak Load .448 .+-. .01 .43 .+-. .01 .42 .+-. .01 .42 .+-. .01 .662
.+-. .013 Perm Set -- -- -- -- -- NSBL No. 1 Cycled in the machine
direction to 46% Elongation Peak TEA .029 .+-. .005 .022 .+-. .003
.021 .+-. .003 .020 .+-. .003 .541 .+-. .11 Peak Load .383 .+-. .09
.355 .+-. .08 .341 .+-. .07 .341 .+-. .07 6.88 .+-. 1.43 Perm Set
6.6 .+-. .1 8 .+-. .6 9.3 .+-. .9 12.6 .+-. .6 90 .+-. 4
__________________________________________________________________________
TABLE 3 ______________________________________ Elastomer Grab
Control NSBL NSBL Tensiles: No. 1 NSBL No. 1 No. 2A No. 2B
______________________________________ MD TEA 1.53 .+-. .25 .21
.+-. .04 .28 .+-. .05 .50 .+-. .04 MD Peak 1.75 .+-. .18 3.4 .+-.
.4 2.82 .+-. .37 2.26 .+-. .2 Load MD Elong 549 .+-. 50 83 .+-. 5
150 .+-. 10 297 .+-. 6 CD TEA 1.44 .+-. .18 .63 .+-. .14 .45 .+-.
11 .40 .+-. .05 CD Peak 1.58 .+-. .08 2.6 .+-. .14 2.52 .+-. .16
2.51 .+-. .21 Load CD Elong 560 .+-. 60 217 .+-. 30 177 .+-. 21 164
.+-. 11 ______________________________________
TABLE 4
__________________________________________________________________________
CYCLE: 1 2 3 4 To Break
__________________________________________________________________________
Elastomer Control No. 1 Cycled in the machine direction ot 46%
Elongation Peak TEA 0.42 .+-. .002 .034 .+-. .002 .033 .+-. .022
.032 .+-. .002 .111 .+-. .003 Peak Load .448 .+-. .01 .43 .+-. .01
.42 .+-. .01 .42 .+-. .01 .662 .+-. .013 Perm Set -- -- -- -- --
NSBL No. 1 Cycled in the machine direction to 46% Elongation Peak
TEA .o29 .+-. .005 .022 .+-. .003 .021 .+-. .003 .020 .+-. .003
.541 .+-. .11 Peak Load .383 .+-. .09 .355 .+-. .08 .341 .+-. .07
.341 .+-. .07 6.88 .+-. 1.43 Perm Set 6.6 .+-. .1 8 .+-. .6 9.3
.+-. .9 12.6 .+-. .6 90 .+-. 4 Elastomer Control No. 1 Cycled in
the machine direction to 84% Elongation Peak TEA .099 .+-. .001
.076 .+-. .001 .073 .+-. .001 .071 .+-. .001 .227 .+-. .003 Peak
Load .615 .+-. .008 .580 .+-. .006 .569 .+-. .007 .561 .+-. .006
.786 .+-. .008 Perm Set -- -- -- -- -- NSBL No. 2A Cycled in the
machine direction to 84% Elongation Peak TEA .053 .+-. .003 .039
.+-. .002 .037 .+-. .002 .036 .+-. .002 .526 .+-. .10 Peak Load
.383 .+-. .03 .34 .+-. .025 .344 .+-. .025 .33 .+-. .02 4.83 .+-.
.6 Perm Set 6 .+-. .6 7.5 .+-. .5 8.3 .+-. .3 11.2 .+-. .7 148 .+-.
9 Elastomer Control No. 1 Cycled in the machine direction to 167%
Elongation Peak TEA .312 .+-. .003 .201 .+-. .003 .19 .+-. .003
.184 .+-. .003 .66 .+-. .01 Peak Load .84 .+-. .014 .78 .+-. .014
.76 .+-. .015 .75 .+-. .01 1.1 .+-. .02 Perm Set -- -- -- -- --
NSBL No. 2B Cycled in the machine direction to 167% Elongation Peak
TEA .166 .+-. .007 .117 .+-. .005 .111 .+-. .004 .107 .+-. .004
.891 .+-. .153 Peak Load .485 .+-. .02 .455 .+-. .02 .44 .+-. .02
.436 .+-. .02 3.88 .+-. .46 Perm Set 6.5 .+-. .2 7.7 .+-. .5 8.4
.+-. .3 9.6 .+-. .5 318 .+-. 15
__________________________________________________________________________
TABLE 5
__________________________________________________________________________
CYCLE: 1 2 3 4 To Break
__________________________________________________________________________
Elastomer Control No. 1 Cycled in the cross-machine direction ot
122% Elongation Peak TEA .17 .+-. .004 .115 .+-. .002 .11 .+-. .001
.104 .+-. .003 .24 .+-. .003 Peak Load .62 .+-. .01 .58 .+-. .006
.57 .+-. .004 .56 .+-. .003 .725 .+-. .003 Perm Set -- -- -- -- --
NSBL No. 2B Cycled in the cross-machine direction to 122%
Elongation Peak TEA .199 .+-. .01 .096 .+-. .005 .09 .+-. .003 .082
.+-. .004 .483 .+-. .04 Peak Load 1.27 .+-. .16 1.13 .+-. .15 1.08
.+-. .13 1.04 .+-. .13 2.46 .+-. .14 Perm Set 12 .+-. 1 14 .+-. .5
14 .+-. .3 16 .+-. 1 184 .+-. 9 Elastomeric Control No. 1 Cycled in
the cross-machine direction to 100% Elongation Peak TEA .132 .+-.
.002 .09 .+-. .001 .09 .+-. .002 .085 .+-. .001 .211 .+-. .004 Peak
Load .575 .+-. .012 .54 .+-. .01 .53 .+-. .01 .52 .+-. .01 .86 .+-.
.01 Perm Set NSBL No. 2A Cycled in the cross-machine direction to
100% Elongation Peak TEA .145 .+-. .03 .075 .+-. .003 .068 .+-. .02
.064 .+-. .002 .462 .+-. .05 Peak Load 1.31 .+-. .28 1.06 .+-. .05
1.0 .+-. .04 .96 .+-. .04 .257 .+-. .14 Perm Set 14 .+-. .3 16 .+-.
.5 17 .+-. .8 18 .+-. 1.5 165 .+-. 7 Elastomer Control No. 1 Cycled
in the cross-machine direction to 92% Elongation Peak TEA .111 .+-.
.005 .08 .+-. .002 .076 .+-. .002 .072 .+-. .001 .214 .+-. .002
Peak Load .549 .+-. .01 .52 .+-. .01 .508 .+-. .01 .50 .+-. .01 .69
.+-. .01 Perm Set -- -- -- -- -- NSBL No. 2B Cycled in the
cross-machine direction to 92% Elongation Peak TEA .136 .+-. .002
.060 .+-. .001 .053 .+-. .001 .050 .+-. .002 .644 .+-. .125 Peak
Load 1.28 .+-. .02 1.12 .+-. .02 1.06 .+-. .02 1.02 .+-. .03 3.52
.+-. .2 Perm Set 163 .+-. 12
__________________________________________________________________________
TABLE 6 ______________________________________ Prestretched
Elastomer Grab Tensiles: Control No. 1 NSBL No. 3A NSBL No. 3B
______________________________________ MD TEA .80 .+-. .26 .36 .+-.
.04 .23 .+-. .03 MD Peak Load 1.38 .+-. .19 3.7 .+-. .42 3.9 .+-.
.2 MD Elong 354 .+-. 70 138 .+-. 15 72 .+-. 6 CD TEA .93 .+-. .23
.42 .+-. .1 .58 .+-. .12 CD Peak Load 1.32 .+-. .13 3.3 .+-. .5
2.53 .+-. .20 CD Elong 450 .+-. 70 150 .+-. 23 194 .+-. 28
______________________________________
TABLE 7
__________________________________________________________________________
CYCLE: 1 2 3 4 To Break
__________________________________________________________________________
NSBL No. 3A Cycled in the machine direction to 78% elongation Peak
TEA .073 .+-. .004 .059 .+-. .003 .052 .+-. .003 .050 .+-. .003 .67
.+-. .07 Peak Load .583 .+-. .04 .51 .+-. .04 .50 .+-. .04 .49 .+-.
.04 5.83 .+-. .52 Perm Set 7 .+-. 1 9 .+-. 1 9 .+-. 1 11 .+-. 1 145
.+-. 8 NSBL No. 3B Cycled in the machine direction to 40%
elongation Peak TEA .038 .+-. .01 .026 .+-. .004 .025 .+-. .003
.024 .+-. .003 .413 .+-. .03 Peak Load .94 .+-. .46 .79 .+-. .33
.77 .+-. .32 .75 .+-. .32 7 .+-. .7 Perm Set 8 .+-. 2 9 .+-. 2 10
.+-. 2 13 .+-. 2 70 .+-. 4 NSBL No. 3B Cycled in the cross-machine
direction to 73% elongation Peak TEA .088 .+-. .007 .051 .+-. .018
.04 .+-. .003 .04 .+-. .003 .571 .+-. .04 Peak Load .65 .+-. .06
.57 .+-. .05 .54 .+-. .04 .53 .+-. .05 2.38 .+-. .2 Perm Set 14
.+-. 1 16 .+-. 1 17 .+-. 1 18 .+-. 1 180 .+-. 8 NSBL No. 3A Cycled
in the cross-machine direction to 84% elongation Peak TEA .071 .+-.
.06 .034 .+-. .02 .03 .+-. .015 .03 .+-. .014 .53 .+-. .09 Peak
Load .66 .+-. .4 .58 .+-. .4 .56 .+-. .3 .54 .+-. .3 4.97 .+-. 1.4
Perm Set 21 .+-. .5 23 .+-. .8 25 .+-. .8 27 .+-. .8 161 .+-. 9
__________________________________________________________________________
TABLE 8
__________________________________________________________________________
Avg. of Reversibly Necked Spunbond Elastomer Prestretched Grab
Tensiles: Nos. 1 & 2 Control No. 1 NSBL No. 4A NSBL No. 4B
Elastomer No. 1 Control No.
__________________________________________________________________________
1 MD TEA .28 .+-. .1 1.53 .+-. .25 .28 .+-. .07 .19 .+-. .03 1.25
.+-. .27 .98 .+-. .2 MD Peak Load 9 .+-. 1 1.75 .+-. .18 3.4 .+-.
.3 4.66 .+-. .61 1.41 .+-. .16 15.1 .+-. 1 MD Elong 18 .+-. 4 550
.+-. 50 110 .+-. 20 32 .+-. 7 550 .+-. 80 40 .+-. 6 CD TEA .53 .+-.
.15 1.44 .+-. .18 .55 .+-. .14 .65 .+-. .10 1.36 .+-. .27 .95 .+-.
.2 CD Peak Load 4.6 .+-. .6 1.58 .+-. .8 2.63 .+-. .20 2.55 .+-.
.06 1.41 .+-. .13 14 .+-. 1 CD Elong 180 .+-. 17 560 .+-. 60 190
.+-. 30 230 .+-. 20 623 .+-. 70 50 .+-. 5
__________________________________________________________________________
TABLE 9
__________________________________________________________________________
CYCLE: 1 2 3 4 To Break
__________________________________________________________________________
NSBL No. 4A Cycled in the machine direction to 60% elongation Peak
TEA .052 .+-. .004 .039 .+-. .002 .037 .+-. .002 .036 .+-. .002
.466 .+-. .132 Peak Load .53 .+-. .10 .50 .+-. .08 .48 .+-. .08 .48
.+-. .08 5.16 .+-. .7 Perm Set 6 .+-. 1 7 .+-. 1 8 .+-. 1 10 .+-. 1
112 .+-. 10 NSBL No. 4A Cycled in the machine direction to 107%
elongation Peak TEA .18 .+-. .01 .07 .+-. .002 .065 .+-. .002 .061
.+-. .002 .43 .+-. .04 Peak Load 1.21 .+-. .08 1.05 .+-. .07 1.0
.+-. .07 .96 .+-. .07 2.96 .+-. .194 Perm Set 20 .+-. 1 23 .+-. 1
24 .+-. 1 27 .+-. 3 166 .+-. 5 NSBL No. 4B Cycled in the
cross-machine direction to 128% elongation Peak TEA .21 .+-. .02
.10 .+-. .01 .09 .+-. .01 .08 .+-. .01 .49 .+-. .05 Peak Load 1.12
.+-. .2 1.0 .+-. .2 .94 .+-. .17 .91 .+-. .17 2.1 .+-. .22 Perm Set
13 .+-. 1 15 .+-. 1 16 .+-. 1 17 .+-. 1 203 .+-. 14
__________________________________________________________________________
TABLE 10 ______________________________________ NSBL No. 2A NSBL
No. 3A ______________________________________ MD TEA .28 .+-. .05
.36 .+-. .04 MD Peak Load 2.82 .+-. .37 3.7 .+-. .42 MD Elong 150
.+-. 10 138 .+-. 15 CD TEA .45 .+-. .11 .42 .+-. .10 CD Peak Load
2.52 .+-. .16 3.3 .+-. .5 CD Elong 177 .+-. 21 150 .+-. 23
______________________________________
TABLE 11
__________________________________________________________________________
CYCLE: 1 2 3 4 To Break
__________________________________________________________________________
NSBL No. 2A Cycled in the machine direction to 84% elongation Peak
TEA .07 .+-. .004 .052 .+-. .003 .050 .+-. .003 .049 .+-. .003 .68
.+-. .10 Peak Load .425 .+-. .02 .40 .+-. .02 .39 .+-. .02 .385
.+-. .02 5.37 .+-. .26 Perm Set 6 .+-. 1 7 .+-. 1 8 .+-. 1 10 .+-.
1 165 .+-. 7 NSBL No. 3A Cycled in the machine direction to 77%
elongation Peak TEA .07 .+-. .009 .054 .+-. .003 .052 .+-. .003 .05
.+-. .003 .67 .+-. .07 Peak Load .54 .+-. .04 .51 .+-. .04 .50 .+-.
.03 .49 .+-. .04 5.83 .+-. .5 Perm Set 7 .+-. 1 9 .+-. 1 9 .+-. 1 1
.+-. 1 145 .+-. 8 NSBL No. 2A Cycled in the cross-machine direction
to 10% elongation Peak TEA .16 .+-. .03 .077 .+-. .01 .07 .+-. .01
.066 .+-. .01 .528 .+-. .05 Peak Load 1.26 .+-. .3 1.1 .+-. .3 1.05
.+-. .25 1.02 .+-. .25 2.9 .+-. .2 Perm Set -- -- -- -- 165 .+-. 11
NSBL No. 3A Cycled in the cross-machine direction to 83% elongation
Peak TEA .07 .+-. .06 .03 .+-. .02 .03 .+-. .02 .03 .+-. .01 .534
.+-. .1 Peak Load .66 .+-. .45 .58 .+-. .4 .56 .+-. .35 .54 .+-.
.33 5.0 .+-. 1.5 Perm Set 21 .+-. .5 23 .+-. 1 25 .+-. 1 27 .+-. 1
161 .+-. 10
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RELATED APPLICATIONS
This application is one of a group of commonly assigned patent
applications which are being filed on the same date. The group
includes the present application and application Ser. No.
07/451,264 entitled "Multi-Direction Stretch Composite Elastic
Material" in the name of Michael T. Morman. The subject matter of
these applications is hereby incorporated herein by reference.
Disclosure of the presently preferred embodiment of the invention
is intended to illustrate and not to limit the invention. It is
understood that those of skill in the art should be capable of
making numerous modifications without departing from the true
spirit and scope of the invention.
* * * * *